Use of native species and biodegradable chelating agents in the phytoremediation of abandoned mining areas

BACKGROUND: The application of phytostabilization and assisted phytoextraction to the remediation of abandoned mining areas can be a valuable method to reclaim these areas without modifying soil and landscape characteristics. An in situ application of a continuous phytoextraction techniquewas carried out in the area of Campo Pisano (Sardinia, Italy), followed by a laboratory assisted phytoextraction test using the biodegradable chelating agents methylglycine diacetic acid (MGDA) and iminodissuccinic acid (IDSA). The plants used were Scrophularia canina subsp. bicolor, Cistus salviifolius and Teucrium flavum subsp. glaucum. RESULTS: The plant that accumulatedmore Pb was T. glaucum (353 mg kg-1)while C. salviifolius demonstrated better ability to accumulate Zn (1560 mg kg-1). S. bicolor showed abetter tolerance to metals but accumulated 119mg kg-1 of Pb. Accumulation of metals immediately after chelant application was up to 300 mg kg-1 of Pb and 3000 mg kg-1 of Zn which did not further increase during the assisted phytoextraction experiment. CONCLUSION: The plant that demonstrated to bemost suitable for phytoremediation applicationwas S. bicolor due to its higher biomass production and tolerance tometals. The low cation exchange capacity and the high concentration of Ca and Mg in soil determined a low chelant effectiveness.